Pogba was forced to pull out of this evening's FA Cup clash with Huddersfield Town on the morning of the game due to illness, raising concerns that he could also be absent when United resume their European duties in Spain next week.
The setback comes amid speculation that Pogba's relationship with Mourinho has broken down, but the Portuguese boss insists that it is merely a case of waiting to see how Pogba's illness develops.
When asked whether Pogba would be available to face Sevilla, Mourinho told BBC Sport: "I don't know, I didn't see him. Yesterday he was working normally with us.
"We prepared for the game, we gave the last touches in the tactical, positional play, we gave the last touches on the set plays and I told the players the team.
"He was in the team but this morning he was not feeling right to play. So he's ill and now we have to wait to see what is going on."